1) Field of the Invention
This invention relates to a tape recorder, and more particularly to improvements in or relating to a tape recorder of the type which includes a rotary member supporting device for supporting a rotary member such as an idler pulley for rotation on a base plate, or a reel receiver mounting mechanism wherein a metal shaft for mounting a reel receiver thereon is supported on a base plate of a synthetic resin material.
2) Description of the Prior Art
A tape recorder normally includes one or more rotary members such as, for example, a pulley and a rotary member supporting device for supporting the rotary member for rotation thereon. Such a rotary member supporting device as shown in FIG. 15 is already known wherein a rotary member a such as a pulley of a tape recorder is supported for rotation on a base plate d made of a synthetic resin material by means of a support shaft f. The support shaft f has an end press fitted in and secured to a shaft fitting hole e formed in the base plate d. The support shaft f is fitted in a center bore c formed in a hub b which is provided projectingly at the center of an axial end face of the rotary member a.
In order to reduce a load to the rotary member against rotation arising from friction between the rotary member a and the support shaft f in the rotary member supporting device, the support shaft f should be reduced in diametrical dimension.
With the rotary member supporting device, however, it is difficult in designing to make the support shaft f very thin because a load applied to the rotary member a is supported only by the support shaft f. If the support shaft f is made excessively thin, then sufficient strength is not assured so that the support shaft f may be bent or deformed when, for example, the support shaft f is press fitted into the shaft fitting hole e or the rotary member a is assembled to the support shaft f, or when an unexpectedly great load is applied to the support shaft f during transportation or the like of the tape recorder, or else when a lateral pressure acts upon the rotary member a.
Meanwhile, even if lubricant such as grease is applied to the support shaft f, such lubricant is partially scraped off when the rotary member a is assembled to the support shaft f. Accordingly, it is difficult to effectively reduce friction between the rotary member a and the support shaft f. Furthermore, as the support shaft f is reduced in thickness and increased in axial length, it becomes more difficult for lubricant to penetrate between the support shaft f and the center bore c of the hub b. Means for resolving the difficulty is thus expected. Besides, dust readily sticks to lubricant on an outer periphery of the support shaft, and there is the possibility that such dust may enter between the support shaft f and the center bore c of the hub b to cause a seizure of the rotary member a or the support shaft f. It is to be noted that reference symbol g in FIG. 15 denotes a member for preventing coming off of the rotary member 1 in a axial direction from the shaft f.
On the other hand, a cassette tape recorder normally includes a reel receiver mounting mechanism for mounting a reel receiver thereon. Such a reel receiver mounting mechanism as shown in FIG. 16 is already known wherein a reel receiver j is mounted for rotation on a metal shaft i and retained in position in an axial direction by means of a washer m. In particular, the metal shaft i is secured at an end thereof to a base plate h formed from a metal plate, and the reel receiver j is fitted for rotation on the metal shaft i. The metal shaft i has an annular groove k formed at the other end portion thereof, and the washer m serving as a coming off preventing member is engaged in the annular groove k of the metal shaft i.
With such a reel receiver mounting mechanism, the metal shaft i is secured at the end thereof to the base plate h normally by "caulking".
Such securing operation by "caulking", however, requires a press fitting device and a crashing device because the securing operation proceeds such that the end portion of the metal shaft i is press fitted into a hole n perforated in advance in the base plate h, and then the end portion of the metal shaft i is crashed on the reverse face side of the base plate h. Besides, it is necessary to assure several dimensions of the metal shaft i and the hole n perforated in the base plate h with a high degree of accuracy.
Meanwhile, in some conventional tape recorders, a base plate is entirely or partly made of a synthetic resin material and a metal shaft is secured at an end portion thereof to the synthetic resin base plate. Also in order to produce such tape recorders, however, it is necessary to use a press fitting device. Besides, where a fitting distance between such base plate and metal shaft is so great that a great press fitting force is required, there is the possibility that the synthetic resin base plate may be damaged. On the contrary, where such fitting distance is very small, only a small press fitting force is required, but reliable fixation cannot be attained.
Accordingly, a higher degree of accuracy in working is required for individual dimensions of a metal shaft and a hole perforated in a base plate made of a synthetic resin material than for dimensions of a base plate formed from a metal plate, resulting in a high production cost.
Further, while conventional cassette tape recorders have various functions such as an automatic reversing function and an automatic stopping function, further miniaturization and reduction in weight is called for such cassette tape recorders in recent years. Accordingly, a cassette tape recorder mechanism is required to meet two apparently inconsistent requirements of improvement in function and of miniaturization and reduction in weight.
In the meantime, as mentioned hereinabove, a base plate for a tape recorder is conventionally formed from a metal plate or from a synthetic resin plate or else from a metal plate and a synthetic resin plate mounted on an upper face of part of the metal plate.
Where a base plate is formed from a metal plate, various support shafts for supporting rotary or pivotal members for rotation or pivotal motion thereon must be mounted on the base plate by caulking or by means of a fastening screw. Accordingly, considerable numbers of parts and man-hours for production are required.
To the contrary, where a base plate is formed from a synthetic resin plate, there is an advantage that parts and man-hours for production can be reduced in number because all shafts or like parts can be formed in an integral relationship with the base plate. It is, however, disadvantageous for reduction of the thickness of an entire tape recorder in that the base plate must have a sufficiently great thickness to compensate for its mechanically low strength.
Where a base plate is formed from a metal plate and a synthetic resin plate mounted on an upper face of part of the metal plate, it has both of the advantages and disadvantages of the two base plates half and half. Thus, while numbers of parts and man-hours for production can be reduced to some degree, such reduction is still insufficient to attain satisfactory reduction in overall thickness of a tape recorder.
Particularly with an automatic reversing tape recorder, because the tape recorder includes a large number of movable parts, reduction in overall thickness is further difficult in spite of such a measure that a plurality of base plates are disposed in a parallel, spaced relationship from each other so as to increase an area in which parts are to be mounted.